SPRUIN7C March 2020 – March 2024 TMS320F280021 , TMS320F280021-Q1 , TMS320F280023 , TMS320F280023-Q1 , TMS320F280023C , TMS320F280025 , TMS320F280025-Q1 , TMS320F280025C , TMS320F280025C-Q1
The FSI module in this device supports multi-slave TDM configurations, whereas a single master device can control multiple slave devices. To use the FSI module in the multi-slave TDM configuration described, the slave device must utilize tag matching and the CLB module.
This multi-slave TDM configuration is supported in the FSI module through time-division multiplexing. When TDM is enabled, each slave device must also have tag matching enabled. Figure 22-10 shows a scheme where a single master device is communicating with multiple slave devices. All FSI receive modules in the slave devices are directly connected to the master device transmit module. The transmit modules of the slave devices are chained serially such that each transmit module is connected to the next slave device and the last slave device output connects to the master device receive module. Each slave device decides, based on the received frame's tag, whether to transmit the data or to enter bypass mode where the previous slave device transmit module directly connects to the next slave device. This is done by using the FSI transmit module TDM_IN.
When an FSI transmitter module is used in TDM mode, TXCLK_TDM_IN, TXD0_TDM_IN and TXD1_TDM_IN pins are used if the transmitter is required to enter bypass mode. Figure 22-11 shows how the FSI module operates when in multi-slave TDM mode.
The SEL_TDM_PATH signal is sourced from the CLB module. The CLB module also generates the transmit trigger for the FSI transmitter. The CLB module must be configured to decide when to generate the FSI transmit trigger based on the status of the data, ping, and frame tag match generated by the FSI receiver module. The FSITX module must be configured to transmit on an external trigger and the corresponding CLB trigger input must be selected. In a broadcast scenario (FSI tag match notifies all slave devices that a match has occurred), the CLB module inside each slave device generates a trigger and SEL_TDM_PATH signal. The main key here is that the trigger and the SEL_TDM_PATH signal must be generated at a different time interval in a non-overlapping manner. Figure 22-12 shows an example of FSI transmit triggers and the multi-slave TDM SEL_TDM_PATH signals generated by the RX_TRIGx signal or the CLB module of the slave devices in a broadcast scenario.